1. Field of the Invention
The present invention relates to instruments for measuring parameters of two-phase flow in pipelines and the like, and particularly to a sensor for two-phase flow measurements.
2. Description of the Related Art
Two-phase flow measurements are very important in the oil and gas, nuclear energy and chemical processing industries. Accurate measurements of the liquid and gas fractions (represented by the void fraction) and the flow pattern are essential for accurate modeling of two-phase flows. Presently, several techniques are used for two-phase flow measurements, including radiation attenuation (X-rays, γ-rays or neutron beams), optical measurement, electrical measurement (either capacitance or resistance impedance), as well as direct volume measurement using quick-closing valves utilized to separate the phases. The selected measuring technique depends on the particular application, and whether a chordal void fraction, a cross-sectional void fraction, a volumetric average void fraction, or a local void fraction is required.
The radiation attenuation method, however, is expensive and, from a safety aspect, difficult to implement. The optical technique disturbs the flow field and is relatively difficult to analyze. Although the impedance measurement technique is relatively practical and cost-effective method for making void fraction measurements, the sensitivity and error involved (due to the background electrical noise in either impedance or capacitance sensors) are major drawbacks to the technique.
Thus, a sensor for two-phase flow measurements solving the aforementioned problems is desired.